DE102011122637A1 - Valve unit with connections for at least two different pressure media - Google Patents

Abstract

The invention relates to a valve assembly (1) with connections (7; 8; 9; 10) for at least two different pressure media, namely compressed air and hydraulic fluid, one pressure medium being used as control medium and the other pressure medium as working fluid, the control medium being a valve (24) switches for the working fluid at least in an open or in a closed position, wherein the valve assembly (1) has a valve housing (2) with two housing halves (3, 4), which the valve assembly (1) in a pneumatic part (5 ) and in a hydraulic part (6) divide. In order to simplify the construction of the valve assembly, it is provided that the pneumatic part (5) is designed as a control chamber and the hydraulic part (6) as a working chamber, wherein a valve designed as a slide (24) is arranged in the hydraulic part (6) a in the pneumatic part (5) arranged, via a compressed air connection (10) acted upon by compressed air control piston (12) is actuated, wherein by actuation of the slide (24) at least one hydraulic input (7) with a hydraulic output (8) is connectable.

Description

The invention relates to a valve assembly with the features of the preamble of claim 1.

Pressurized valve assemblies are well known. In general, valve assemblies are operated only with a pressure medium, so either pneumatically with compressed air, or hydraulically with a hydraulic fluid.

However, mixed forms have also been described. That's how it describes DE 29 07 426 C2 a motor vehicle brake system, is controlled at the pneumatic pressure and passed to pneumatic brake cylinder. Here, hydraulic pressure is used to control the pneumatic valve.

Also known are so-called "Air over Hydraulic" systems, short: AoH, in which compressed air is converted via a pressure transducer into hydraulic pressure. An example of such an AoH system will be found in the DE 197 46 030 A1 described. A disadvantage of these systems is the spatially trained pressure transducer. Due to the system, this must be designed to be very large, since it must be able to convert pneumatic pressure of the order of magnitude of 8 to 12 bar into hydraulic pressure of the order of magnitude greater than 100 bar. Such pressure transducers are not only very expensive to produce and therefore expensive, they can not be installed in any vehicle, since not always enough space is available for this purpose.

The invention has for its object to provide a valve assembly with which can easily convert pneumatic input pressure in hydraulic output pressure.

The invention is based on the finding that the stated object can be achieved in a surprisingly simple manner with a valve assembly having the features of claim 1.

By this construction, on the one hand achieved that in relation to the hydraulic pressure low pneumatic pressure can be used without complicated and constructive measures as such, without a pressure conversion to a much higher pressure level would be necessary. The pneumatic pressure is used as a pure control pressure by the pneumatic pressure is applied to a simple constructed control piston. This control piston is used exclusively to actuate the valve of the hydraulic part of the valve assembly.

In addition, it can be provided that the control pressure acting on the control piston of the pneumatic part is between 8.5 and 12.5, preferably 10 bar, and that the hydraulic pressure applied to the hydraulic input of the hydraulic part is between 85 and 125 bar, preferably 100 bar , wherein the pressure ratio has a ratio of 10: 1.

In other practical developments can be provided that the control piston transmits the pressure acting on it via a plunger on a first spring plate, wherein the first spring plate is disposed in an axial cylinder bore of the housing half of the hydraulic part of the valve assembly, wherein the first spring plate with an edge against a pneumatic part facing the end of a helical compression spring is supported, with a facing to the hydraulic connections end of the helical compression spring is supported against an edge of a second spring plate, which bears against the slider.

Another embodiment of the invention provides that the slide is arranged longitudinally displaceable in a cylindrical bore in the housing half of the hydraulic part, wherein the diameter of the bore is smaller in diameter than the cylinder bores of the housing halves.

Likewise, it is within the scope of the invention to provide that the ratio of the diameter of the slide to the diameter of the control piston is about 1: 3.

In a particularly preferred embodiment of the invention it is provided that the valve assembly is part of a brake system of a motor vehicle, in particular an agricultural tractor, wherein the brake system is hydraulically and control side pneumatically formed on the driver side.

In a particularly practical embodiment of the invention it is provided that wheels of the vehicle each have brakes which are actuated by a respective hydraulic brake cylinder, wherein the brake cylinders are connected to at least one hydraulic accumulator, wherein between the at least one hydraulic accumulator and the hydraulic brake cylinders each have a valve assembly is arranged.

Also particularly advantageous is an embodiment of the invention, which is characterized in that the brake system control side has at least one compressed air tank, from which compressed air in each case in the compressed air connection of the valve assembly can be fed, wherein between the at least one compressed air tank and one each Valve unit, a brake value transmitter is arranged in the form of a foot brake valve.

In a particularly practical development of the invention, it is provided that the brake system on the control side components of a pneumatic ABS brake system, in particular pneumatic ABS valves, which are arranged between the brake signal transmitter and each a valve assembly.

This embodiment can be supplemented in that the ABS brake system is electronically controlled by an electronic control unit, wherein at least electric speed sensors for detecting rotational speeds of the wheels are arranged thereon and electrically connected to the control unit.

In this case, according to a practical supplement, provision can be made for a 3/2-way valve electronically controlled by the control unit to be arranged between the at least one compressed air reservoir and at least one ABS valve.

This embodiment can also be supplemented by the fact that the 3/2-way valve allows autonomous steering brake function.

Finally, an embodiment of the invention is particularly advantageous, which is characterized in that the 3/2-way valve is so switchable in the presence of a detected by the electronic control unit steering brake request due to the speed sensor and a steering wheel angle sensor data about vehicle speed and steering angle, that a axle-wise, one-sided braking of wheels takes place or is suppressed.

The invention will be explained in more detail below with reference to the accompanying drawings. It shows

1 an embodiment of a valve assembly according to the invention in longitudinal section,

2 the valve assembly off 1 in 90 ° rotated sectional view, and

3 a schematic circuit diagram of a brake system using the valve assembly according to the invention.

Accordingly, shows 1 and 2 An embodiment of a valve assembly according to the invention 1 , in 1 in longitudinal section and in 2 in partial longitudinal section in opposite 1 90 ° rotated view. The valve assembly 1 has a centrally split valve body 2 with two housing halves 3 . 4 on which the valve assembly 1 in a pneumatic part 5 and in a hydraulic part 6 divide. The housing halves 3 . 4 lie with front edges 3a . 4a on each other and are with bolts 3b . 4b connected with each other.

The hydraulic part 6 the valve assembly 1 has a total of three connections for hydraulic fluid as a working fluid, namely a hydraulic input 7 , a hydraulic outlet 8th and a hydraulic return 9 , where entrance 7 and return 9 only in 1 and the exit 8th only in 2 are recognizable because entrance 7 and return 9 offset by 90 ° to the return 8th on the hydraulic part 6 are arranged. The connections 7 - 9 are connected via hydraulic lines, not shown, with one or more non-illustrated storage of hydraulic fluid. The hydraulic part forms the actual valve for hydraulic fluid to be fed or represents a working chamber for the hydraulic fluid.

The pneumatic part 5 the valve assembly 1 has a pneumatic compressed air connection 10 for feeding compressed air into the pneumatic part 5 on. The compressed air connection 10 is connected via a compressed air line, not shown, with an air pressure source, not shown. The pneumatic part 5 represents the control or switching chamber with which the valve of the hydraulic part 6 operated, that is switched. Accordingly, the hydraulic part 6 the working chamber

The operation of the valve assembly 1 is the following: as soon as need exists, one with the hydraulic output 8th connected, not shown, the pressure, for example, a brake cylinder to pressurize with hydraulic pressure, is used as a control pressure compressed air via the compressed air connection 10 in the pneumatic part 5 the valve assembly 1 fed. The compressed air is acted upon at a pressure of about 10 bar one in an axial cylinder bore 11 arranged control piston 12 , This transmits the pressure acting on him via a plunger 13 on a first spring plate 14 , where the first spring plate 14 and the components listed below in an axial cylinder bore 15 the housing half 4 of the hydraulic part 6 the valve assembly 1 is arranged.

The first spring plate 14 rests with a brim 16 against to the pneumatic part 5 clever finish 17 a helical compression spring 18 from. One to the hydraulic connections 7 - 9 wayward end 19 the helical pressure fader 18 rests against a brim 20 a second spring plate 21 from. The second spring plate 21 is opposite the first spring plate 14 arranged mirror-inverted and has a hemispherical plate bottom 22 in which a ball 23 is arranged, which on a spring-loaded slide 24 is present or with this connected is. The slider 24 , which represents the actual valve, is longitudinally displaceable in a cylindrical bore 25 arranged, with the diameter of the bore 25 smaller in diameter than the cylinder bores 11 and 15 the housing halves 3 . 4 , Accordingly, the diameter of the slider 24 less than the diameter of the control piston 12 , In the illustrated embodiment, the ratio of the diameter of the slider 24 to the diameter of the control piston 12 about 1: 3. One in a recess 26 arranged seal 27 Make sure that no hydraulic fluid from the hydraulic part 6 in the pneumatic part 5 can escape. Also, by the seal 27 ensures that no compressed air from the pneumatic part 5 in the hydraulic part 6 can penetrate.

The slider 24 is designed in a conventional manner so that - depending on the axial position - the hydraulic connections 7 - 9 separates or connects with each other. In this respect, the slider forms 24 a 2-way valve, turns off the hydraulic part 6 So either on or to, which by the slide 24 formed valve is normally closed. Front side is in the cylindrical bore 25 the housing half 4 of the hydraulic part 6 a screw 28 screwed. Between the screw 28 and a face 29 of the slider 24 is a compression spring 30 arranged. By appropriate rotation of the screw 28 can be the spring force of the compression spring 30 and with it on the slide 24 adjust acting preload.

Will now be necessary if a control pressure exerting compressed air in the valve assembly 1 fed, the slider shifts 24 towards the screw 28 , resulting in a connection of the hydraulic connections 7 - 9 leads. As long as pneumatic control pressure at about 8.5 to 12.5 bar, preferably at 10 bar on the slide 24 acts, the connections remain 7 - 9 open and hydraulic fluid can with a pressure of about 85 to 125 bar, preferably with 100 bar from the entrance 7 to the exit 8th flow, whereby the hydraulic slave is subjected to hydraulic pressure. The pressure ratio thus has a ratio of 10: 1.

The relevant items have the following dimensions in the embodiment: diameter of the control piston 12 : 46.1 mm, piston stroke of the spool 12 : between 9.5 and 15 mm, pneumatic volume between 15.9 and 25.1 cc.

The previously described construction of the valve assembly 1 allows a particularly compact and lightweight valve assembly 1 , which offers particular advantages over previously known "Air over Hydraulic" pressure converters.

A particularly preferred application of the valve assembly 1 is in 3 shown. This shows a schematic plan a brake circuit diagram of a brake system 31 an indicated in dotted lines motor vehicle in the form of an agricultural tractor 32 , In principle, the brake system described in more detail below can be 31 but also for other types of motor vehicles, for example, medium-heavy trucks, construction machinery, forestry-used articulated tractors or wheel loaders.

The tractor has steerable front wheels 33 . 34 and rigid rear wheels 35 . 36 on. front wheels 33 . 34 and rear wheels 35 . 36 in the following are summarized as wheels 33 - 36 designated. The wheels 33 - 36 are each equipped with a brake known per se, of which in each case only schematically a brake cylinder 37 - 40 is shown. As usual, the brake system 31 two-circle formed, wherein the brake cylinder 37 . 38 the front wheels 33 . 34 at a first brake circuit I and the brake cylinders 39 . 40 the rear wheels 35 . 36 are connected to a second brake circuit II. The respective hydraulic brake cylinder 37 . 38 the front wheels 33 . 34 are with a hydraulic accumulator 41 connected, wherein it is in the hydraulic accumulator 41 is a high-pressure accumulator, which is applied in a suitable manner with high pressure. Accordingly, the respective hydraulic brake cylinder 39 . 40 the rear wheels 35 . 36 with a hydraulic accumulator 42 connected, wherein it is in the hydraulic accumulator 42 also is a high-pressure accumulator, which is applied in a suitable manner with high pressure.

Between the hydraulic accumulators 41 . 42 and the brake cylinders 37 - 40 each is a valve assembly 1 according to the 1 and 2 arranged.

While the brake system 31 So slave side is so hydraulically formed, it is donor or control side pneumatically formed. According to the two-circuit design of the brake system, the pneumatic control unit has two compressed air tanks 43 . 44 , wherein the compressed air tank 43 the brake circuit I and the compressed air tank 44 assigned to the brake circuit II. The compressed air tank 43 . 44 be filled in a manner not shown, in a known manner with compressed air, which is usually done via a compressor system with intermediate air dryer system. The compressed air tank 43 . 44 are to compressed air lines not provided in detail with reference numbers to a brake value transmitter 45 in the form of a dual-circuit foot brake valve 46 connected.

When the foot brake valve is actuated 46 Compressed air comes from the compressed air tanks 43 . 44 to the respective compressed air connection 10 the respective valve assembly 1 , which ensures that in 3 not shown slider 24 the valve assembly 1 shifted and consequently hydraulic fluid in the brake cylinder 37 - 40 is pumped.

To optimize the braking effect are in the brake system 31 further, known per se components of a pneumatic, electronically controlled ABS brake system provided, which on the basis of the first brake circuit I of the front wheels 33 . 34 is described. Components of ABS brake system of the second brake circuit II of back wheels 35 . 36 are built up or installed accordingly.

An electronic control unit 47 is electric with wheel speed sensors 48 each of the wheels 33 - 36 connected, for simplicity, only the speed sensor 48 the right front wheel 33 is provided with a reference numeral. The control unit 47 is electrically connected in a manner not shown with other electrical and electronic components, such as switches, the accumulator of the tractor 32 , Warning and indicator lights in the dashboard, according to a CAN bus line SAE J1939 , and the same. Also electrically via an electrical line is the control unit 47 with a pressure sensor 49 connected, which air pressure or pneumatic output control pressure in an output pressure line of the two-circuit foot brake valve 46 detected. A - not shown - electrical control line exists between the control unit 47 and a 3/2-way valve 50 , which directly to the compressed air tank 43 connected. This is about a double check valve 51 with an ABS valve 52 connected, the ABS valve 52 on the output side finally with the compressed air connection 1 the valve assembly 10 connected is.

The 3/2-way valve 50 Serves optional functions, such as active braking intervention independent of the driver's request, ASC (Autonomous Stability Control) and other functions. The electronically controlled 3/2-way valve 50 can also come to an end. But is preferred in 3 illustrated embodiment with the 3/2-way valve, as can be made possible by this special features. This can be done by means of the 3/2-way valve 50 realize a steering brake function in a particularly simple manner. Detects the controller 47 due to the speed of the wheels 33 - 36 at a low speed, what the controller 47 can interpret on a drive off paved roads, and recognizes the controller 47 due to a steering wheel angle sensor 53 a sudden steering wheel lock, recognizes the controller 47 The desire of the driver to want to drive a sharp turn when driving in the field. Then the wheels become 33 - 36 braked on one side, ie, at the request of the driver to want to drive a tight left turn, the left front wheel 34 and the left rear wheel 36 braked, while the outside wheels 33 . 35 not be slowed down. When driving on roads, this feature is provided by the controller 47 autonomously overruled, so that then a one-sided braking is excluded.

In the above manner, a steering brake function is made possible in the simplest way, so that it is then possible to make do with only one foot brake lever or only one foot brake valve, while usually usually two agricultural tractor tractors two Fußbremshebel are arranged, which when driving on normal roads with each other must be connected so that a steering brakes is excluded when driving on the road.

In particular in connection with the 1 and 2 described, pneumatically controlled or pilot-controlled valve assembly 1 allows the use of existing or known components for generating a pneumatic control pressure and the control of a hydraulic pressure in a simple manner. If the valve assembly is used in a motor vehicle brake system, as in connection with 3 For example, simple pneumatic control components may be used to control faster-acting hydraulic wheel brake components. At the same time, the use of expensive and bulky constructed pneumatic-hydraulic pressure converter, as they are known from conventional AoH systems, can be dispensed with.

LIST OF REFERENCE NUMBERS

1

valve assembly

2

valve housing

3

housing half

3a

front edge

3b

bolts

4

housing half

4a

front edge

4b

bolts

5

Pneumatic part

6

Hydraulic part

7

Hydraulic input

8th

Hydraulic output

9

Hydraulic return

10

Compressed air connection

11

bore

12

spool

13

tappet

14

First spring plate

15

bore

16

edge

17

The End

18

Helical compression spring

19

The End

20

edge

21

Second spring plate

22

Tellerboden

23

Bullet

24

pusher

25

drilling

26

recess

27

poetry

28

screw

29

face

30

compression spring

31

braking system

32

tractor

33

front

34

front

35

rear wheel

36

rear wheel

37

brake cylinder

38

brake cylinder

39

brake cylinder

40

brake cylinder

41

hydraulic accumulator

42

hydraulic accumulator

43

Air receiver

44

Air receiver

45

Brake signal transmitter

46

Dual circuit foot brake

47

control unit

48

wheel speed sensor

49

pressure sensor

50

3/2-way valve

51

Double check valve

52

ABS valve

53

Steering angle sensor

I

first brake circuit

II

second brake circuit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2907426 C2 [0003]
• DE 19746030 A1 [0004]

Cited non-patent literature

• SAE J1939 [0039]

Claims (13)

Valve assembly ( 1 ) with connections ( 7 ; 8th ; 9 ; 10 ) for at least two different pressure media, namely compressed air and hydraulic fluid, wherein a pressure medium is used as the control medium and the other pressure medium as the working medium, wherein the control medium is a valve ( 24 ) switches for the working medium at least in an open or in a closed position, wherein the valve assembly ( 1 ) a valve housing ( 2 ) with two housing halves ( 3 . 4 ), which the valve assembly ( 1 ) in a pneumatic part ( 5 ) and in a hydraulic part ( 6 ), characterized in that the pneumatic part ( 5 ) as a control chamber and the hydraulic part ( 6 ) is designed as a working chamber, with a slide ( 24 ) formed valve in the hydraulic part ( 6 ), which by means of a in the pneumatic part ( 5 ), via a compressed air connection ( 10 ) can be acted upon with compressed air control piston ( 12 ) is actuated, wherein by actuation of the slide ( 24 ) at least one hydraulic input ( 7 ) with a hydraulic output ( 8th ) is connectable. Valve assembly according to claim 1, characterized in that on the control piston ( 12 ) of the pneumatic part ( 5 ) acting control pressure between 8.5 and 12.5, preferably 10 bar and that at the hydraulic input ( 7 ) of the hydraulic part ( 6 ) applied hydraulic pressure between 85 and 125 bar, preferably 100 bar, wherein the pressure ratio has a ratio of 10: 1. Valve assembly according to claim 1 or 2, characterized in that the control piston ( 12 ) the pressure acting on it via a plunger ( 13 ) on a first spring plate ( 14 ), wherein the first spring plate ( 14 ) in an axial cylinder bore ( 15 ) of the housing half ( 4 ) of the hydraulic part ( 6 ) of the valve assembly ( 1 ) is arranged, wherein the first spring plate ( 14 ) with an edge ( 16 ) against a to the pneumatic part ( 5 ) end turned ( 17 ) a helical compression spring ( 18 ), wherein one of the hydraulic connections ( 7 - 9 ) end ( 19 ) of the helical compression spring ( 18 ) against a border ( 20 ) a second spring plate ( 21 ) is supported, which on the slide ( 24 ) is present. Valve assembly according to claim 3, characterized in that the slide ( 24 ) longitudinally displaceable in a cylindrical bore ( 25 ) in the housing half ( 4 ) of the hydraulic part ( 6 ), wherein the diameter of the bore ( 25 ) smaller in diameter than the cylinder bores ( 11 . 15 ) of the housing halves ( 3 . 4 ). Valve assembly according to claim 4, characterized in that the ratio of the diameter of the slide ( 24 ) to the diameter of the control piston ( 12 ) is about 1: 3. Valve assembly according to at least one of claims 1-5, characterized in that the valve assembly ( 1 ) Part of a brake system ( 31 ) of a motor vehicle, in particular an agricultural tractor ( 32 ), the brake system ( 31 ) Hydraulic and tax-side pneumatically formed on the subscriber side. Valve assembly according to claim 6, characterized in that wheels ( 33 - 36 ) of the vehicle ( 32 ) each have brakes, which in each case by a hydraulic brake cylinder ( 37 - 40 ) are actuated, wherein the brake cylinder ( 37 - 40 ) on at least one hydraulic accumulator ( 41 ; 42 ) are connected, wherein between the at least one hydraulic accumulator ( 41 ; 42 ) and the hydraulic brake cylinders ( 37 - 40 ) each have a valve assembly ( 1 ) is arranged. Valve assembly according to claim 6 or 7, characterized in that the brake system ( 31 ) control side at least one compressed air tank ( 43 ; 44 ), from which compressed air in each case in the compressed air connection ( 10 ) of the valve assembly ( 1 ) is fed, wherein between the at least one compressed air tank ( 43 ; 44 ) and one valve assembly ( 1 ) a brake value transmitter ( 45 ) in the form of a foot brake valve ( 46 ) is arranged. Valve assembly according to at least one of claims 6-8, characterized in that the brake system ( 31 ) control components of a pneumatic ABS brake system, in particular pneumatic ABS valves ( 52 ), which between brake value transmitter ( 45 ) and one valve assembly ( 1 ) are arranged. Valve assembly according to 9, characterized in that the ABS brake system electronically by an electronic control unit ( 47 ), wherein at least electrical speed sensors ( 48 ) for detecting rotational speeds of the wheels ( 33 - 36 ) and electrically connected to the control unit ( 47 ) are connected. Valve assembly according to claim 10, characterized in that between the at least one compressed air tank ( 43 ; 44 ) and at least one ABS valve ( 52 ) through the control unit ( 47 ) electronically controlled 3/2-way valve ( 50 ) is arranged. Valve assembly according to claim 11, characterized in that the 3/2-way valve ( 50 ) allows an autonomous steering brake function. Valve assembly according to claim 12, characterized in that the 3/2-way valve ( 50 ) in the presence of one of the electronic control unit ( 47 ) recognized steering brake request due to by the speed sensors ( 48 ) and by a steering wheel angle sensor ( 53 ) data on vehicle speed and steering wheel angle is switchable in such a way that an axle-sided, one-sided braking of wheels ( 33 . 35 ; 34 . 36 ) takes place or is suppressed.

Images